I use an 8 gallon round Gott cooler with braid - got everything at my local menards many years ago. Still going strong, however, I recently converted a much larger coleman cooler so I could make bigger beers.

I use a 10 gallon stainless steel pot for big beers a 5 gallon pot for regular ones. Insulation did not seem to be a big problem (it cools down at around 2°F in 30 min, but I compensate for that with heating) and temperature control is very easy, because they can be heated on the stove. The 10 gallon pot I also use for boiling. During sparging there is enough time to clean the guy. I normally get 75 % efficiency.

The 50-something quart Coleman Xtreme here as well with the braid configuration straight from Denny's site. I bought all the materials for a fancy drain valve, but since I couldn't find SS washers, I went with the drilled stopper method and never looked back.

After reading all these posts I have a bit of mash tun envy. I have a 5 gallon Rubbermaid cooler with a stainless false bottom. It works great but only holds about 14 lb of grain. It's usually not a big deal since most of my beers are in the 1.045 to 1.060 range. Anything over that, I have to suppliment with extract. I may go up to a 10 gallon some day, but for now it works great.